1. Field of the Invention
The present invention relates to a technique for recording an image on a recording medium by irradiation with light.
2. Description of the Background Art
Developed has been a light modulator element of diffraction grating type which is capable of changing the depth of grating by alternately forming fixed ribbons and moving ribbons on a substrate with a semiconductor device manufacturing technique and sagging the moving ribbons relatively to the fixed ribbons. It is proposed that such a diffraction grating is used for light modulation in an image recording apparatus for recording an image on various recording mediums, since the intensities of normally reflected light and diffracted light are changed by changing the depth of grooves on the diffraction grating.
For example, a plurality of light modulator elements of diffraction grating type provided in the image recording apparatus are irradiated with light, and then reflected light (zeroth order light) from light modulator elements in a state where the fixed ribbons and the moving ribbons are positioned at the same height from a base surface is guided to the recording medium and non-zeroth order diffracted light (mainly first order diffracted light) from light modulator elements in a state where the moving ribbons are sagged is blocked, to achieve an image recording on the recording medium.
Japanese Patent Application Laid Open No. 2004-4525 (Document 1) discloses a technique correcting the timing of transition between ON and OFF states of a light modulator element in such an image recording apparatus to correct asymmetry between transition from the OFF state to the ON state and transition from the ON state to the OFF state, difference in characteristics of photosensitive materials, and positional shifts of writing regions caused by difference in length or position of irradiation regions of light modulator elements in a scan direction.
In the image recording apparatus of Document 1, however, since one clock is selected from a group of clocks, which are sequentially shifted by a small time period, within a time period corresponding to one pixel and a driving voltage according to a pixel value of a pixel corresponding to the clock is inputted to a light modulator element, it is not possible to shift a transition timing in excess of the time period corresponding to one pixel (or shift a transition position in excess of the distance corresponding to one pixel).